| Message ID | 20230531101736.12981-3-frederic@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | rcu: Support for lazy callbacks on !CONFIG_RCU_NOCB_CPU | expand |
On Wed, May 31, 2023 at 6:17 AM Frederic Weisbecker <frederic@kernel.org> wrote: > > This makes the code more readable. > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> > --- > kernel/rcu/rcu_segcblist.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c > index f71fac422c8f..1693ea22ef1b 100644 > --- a/kernel/rcu/rcu_segcblist.c > +++ b/kernel/rcu/rcu_segcblist.c > @@ -368,7 +368,7 @@ bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, > smp_mb(); /* Ensure counts are updated before callback is entrained. */ > rhp->next = NULL; > for (i = RCU_NEXT_TAIL; i > RCU_DONE_TAIL; i--) > - if (rsclp->tails[i] != rsclp->tails[i - 1]) > + if (!rcu_segcblist_segempty(rsclp, i)) Hopefully the compiler optimizer will be smart enough to remove this from the inlined code ;-): if (seg == RCU_DONE_TAIL) return &rsclp->head == rsclp->tails[RCU_DONE_TAIL]; Otherwise it appears to be no functional change for this and the below change, and straightforward so for this patch: Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> thanks, - Joel > break; > rcu_segcblist_inc_seglen(rsclp, i); > WRITE_ONCE(*rsclp->tails[i], rhp); > @@ -551,7 +551,7 @@ bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq) > * as their ->gp_seq[] grace-period completion sequence number. > */ > for (i = RCU_NEXT_READY_TAIL; i > RCU_DONE_TAIL; i--) > - if (rsclp->tails[i] != rsclp->tails[i - 1] && > + if (!rcu_segcblist_segempty(rsclp, i) && > ULONG_CMP_LT(rsclp->gp_seq[i], seq)) > break; > > -- > 2.40.1 >
This patch LGTM. Thanks! Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com> > From: Frederic Weisbecker <frederic@kernel.org> > Sent: Wednesday, May 31, 2023 6:17 PM > To: Paul E . McKenney <paulmck@kernel.org> > Cc: LKML <linux-kernel@vger.kernel.org>; Frederic Weisbecker > <frederic@kernel.org>; rcu <rcu@vger.kernel.org>; Uladzislau Rezki > <urezki@gmail.com>; Neeraj Upadhyay <quic_neeraju@quicinc.com>; Joel > Fernandes <joel@joelfernandes.org>; Giovanni Gherdovich > <ggherdovich@suse.cz> > Subject: [PATCH 2/9] rcu: Use rcu_segcblist_segempty() instead of open > coding it > > This makes the code more readable. > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> > --- > kernel/rcu/rcu_segcblist.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c index > f71fac422c8f..1693ea22ef1b 100644 > --- a/kernel/rcu/rcu_segcblist.c > +++ b/kernel/rcu/rcu_segcblist.c > @@ -368,7 +368,7 @@ bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, > smp_mb(); /* Ensure counts are updated before callback is entrained. > */ > rhp->next = NULL; > for (i = RCU_NEXT_TAIL; i > RCU_DONE_TAIL; i--) > - if (rsclp->tails[i] != rsclp->tails[i - 1]) > + if (!rcu_segcblist_segempty(rsclp, i)) > break; > rcu_segcblist_inc_seglen(rsclp, i); > WRITE_ONCE(*rsclp->tails[i], rhp); > @@ -551,7 +551,7 @@ bool rcu_segcblist_accelerate(struct rcu_segcblist > *rsclp, unsigned long seq) > * as their ->gp_seq[] grace-period completion sequence number. > */ > for (i = RCU_NEXT_READY_TAIL; i > RCU_DONE_TAIL; i--) > - if (rsclp->tails[i] != rsclp->tails[i - 1] && > + if (!rcu_segcblist_segempty(rsclp, i) && > ULONG_CMP_LT(rsclp->gp_seq[i], seq)) > break; > > -- > 2.40.1
Le Fri, Jun 02, 2023 at 07:00:00PM -0400, Joel Fernandes a écrit : > On Wed, May 31, 2023 at 6:17 AM Frederic Weisbecker <frederic@kernel.org> wrote: > > > > This makes the code more readable. > > > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> > > --- > > kernel/rcu/rcu_segcblist.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c > > index f71fac422c8f..1693ea22ef1b 100644 > > --- a/kernel/rcu/rcu_segcblist.c > > +++ b/kernel/rcu/rcu_segcblist.c > > @@ -368,7 +368,7 @@ bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, > > smp_mb(); /* Ensure counts are updated before callback is entrained. */ > > rhp->next = NULL; > > for (i = RCU_NEXT_TAIL; i > RCU_DONE_TAIL; i--) > > - if (rsclp->tails[i] != rsclp->tails[i - 1]) > > + if (!rcu_segcblist_segempty(rsclp, i)) > > Hopefully the compiler optimizer will be smart enough to remove this > from the inlined code ;-): > if (seg == RCU_DONE_TAIL) > return &rsclp->head == rsclp->tails[RCU_DONE_TAIL]; I'm counting on that indeed :-) > > Otherwise it appears to be no functional change for this and the below > change, and straightforward so for this patch: > Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Thanks.
diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c index f71fac422c8f..1693ea22ef1b 100644 --- a/kernel/rcu/rcu_segcblist.c +++ b/kernel/rcu/rcu_segcblist.c @@ -368,7 +368,7 @@ bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, smp_mb(); /* Ensure counts are updated before callback is entrained. */ rhp->next = NULL; for (i = RCU_NEXT_TAIL; i > RCU_DONE_TAIL; i--) - if (rsclp->tails[i] != rsclp->tails[i - 1]) + if (!rcu_segcblist_segempty(rsclp, i)) break; rcu_segcblist_inc_seglen(rsclp, i); WRITE_ONCE(*rsclp->tails[i], rhp); @@ -551,7 +551,7 @@ bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq) * as their ->gp_seq[] grace-period completion sequence number. */ for (i = RCU_NEXT_READY_TAIL; i > RCU_DONE_TAIL; i--) - if (rsclp->tails[i] != rsclp->tails[i - 1] && + if (!rcu_segcblist_segempty(rsclp, i) && ULONG_CMP_LT(rsclp->gp_seq[i], seq)) break;
This makes the code more readable. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> --- kernel/rcu/rcu_segcblist.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)